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  Ciphering key management and distribution in mbmsUSPTO Application #: 20060140411Title: Ciphering key management and distribution in mbms Abstract: A method for key management and assignment in MBMS service, the method includes following steps: the group key locates in the root node on the highest layer, which only has child nodes and doesn't have parent nodes; private keys corresponding to users locate in leaf nodes; the described intermediate node that owns both one parent node and one or more child nodes holds it own key. This invention deploys the method of combining point-to-point mode and point-to-multipoint mode during the process of key update; compared with the key update method only deploying point-to-point mode, this method can reduce the times necessary for information transmission, reduce the system load as well as the time needed for one key update process. Compared with the key update method only deploying point-to-multipoint mode, this solves the security problem of key exposure. (end of abstract) Agent: Dilworth & Barrese, LLP - Uniondale, NY, US Inventor: Yanmin Zhu USPTO Applicaton #: 20060140411 - Class: 380277000 (USPTO) Related Patent Categories: Cryptography, Key Management The Patent Description & Claims data below is from USPTO Patent Application 20060140411. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to Multimedia Broadcast and Multicast Service (hereinafter referred to as MBMS) and more particularly, relates to a method for key management and assignment in Multimedia Broadcast and Multicast Service. [0003] 2. Description of the Prior Art [0004] MBMS is a new service under standardization by 3.sup.rd Generation Mobile Communication System Partnership Project. MBMS service is an unidirectional point-to-multipoint (p-t-m) (i.e. multimedia data sent from a single data source are transferred to multiple users through mobile communication network) service, whose most remarkable characteristic is that it can make use of radio resources and network resources efficiently. MBMS service is mainly used in wireless communication network system, e.g. Wideband Code-Division Multiple Access system, Global System for Mobile Communication, etc. MBMS service data transfer basically includes following several steps, i.e. data source transmission, intermediate network transmission, destination cell on-air transmission and user reception. FIG. 16 is the logical figure for network devices of the radio communication system that can provide MBMS service, in which MBMS actually makes use of General Packet Radio Data Service (hereinafter referred to as GPRS) as core transmission network. As shown in FIG. 16, Broadcast and Multicast Service Center (hereinafter referred to as BM-SC) is the data source for MBMS data transmission; Gateway GPRS Supporting Node (hereinafter referred to as GGSN) is used to connect GRPS network with external network such as INTERNET. in MBMS service, GGSN is used to comnect BM-SC and to send MBMS data to specific Serving GPRS Supporting Node (hereinafter referred to as SGSN); Cell Broadcast Center (hereinafter referred to as CBC) is the data resource of cell broadcast. CBC can be allowed to provide MBMS service announcing function by interconnecting CBC with BM-SC in MBMS; SGSN is used to perform access control and mobility management on UE, and also sends MBMS data from GGSN to specific Radio Network Controller (hereinafter referred to as RNC) at the same time; RNC is used to control a group of Node B and sends multimedia data to specific NODE B; NODE B establishes on-air physical channel for MBMS service in a certain cell under the control of RNC; Terminal User Equipment (hereinafter referred to as UE) is the terminal equipment for MBMS data reception. [0005] In FIG. 17, it provides the whole process from service announcement, user joining, service notification, radio bearer set up till user's final leaving in MBMS service. [0006] 000 Subscription--Establish the connection between user and service provider. Authorized user can receive relevant MBMS service. [0007] 001 Service announcement--Inform user of services that will be provided. For example, the system will rebroadcast a football match in Beijing at 7:00 p.m. [0008] 002 Joining--Indicate that user joins a group, i.e. the user informs the is network that he or she is willing to receive this multicast service. [0009] 003 MBMS multicast bearer set up--Establish network resources for MBMS data transfer. [0010] 004 MBMS notification--Inforn user about forthcoming (and potentially about ongoing) MBMS data transfer. [0011] 005 Data transfer--Indicate the process of transferring MBMS service data to user. [0012] 006 MBMS multicast bearer release--Release network resources when MBMS service data transfer is finished. [0013] 007 Leaving corresponds to 002 joining, and indicates that a user is leaving a group, i.e. the user doesn't want to receive the data of a certain service any more. [0014] In a wireless communication network system, information exchange between a user and the network system is to be accomplished via transmission channels. Generally there are two kinds of transmission channels in wireless communication network system, i.e. dedicated channel occupied by a single user or common channel shared by multiple users. Generally, transmission based on point-to-point (i.e. the data sent from a data source are transferred to one user for receiving through network transmission) is achieved via dedicated channel, while transmission based on point-to-multipoint is achieved via common channel. In common, to guarantee the security of data transmission on a dedicated channel occupied solely by a user, each user connected to the wireless communication network system owns a private key that is only known by himself/herself and the network system; data transmission conducted on the dedicated channel between the user and the network system are encrypted by the private key. And as a common channel is shared by multiple users, data transmission on the common channel generally is not encrypted. To make use of radio resources and network resources efficiently, MBMS service data can be transmitted via common channel. At this time, taking aspects such as accounting and security into account, MBMS service data transnitted via common channels generally need to be encrypted to ensure that those data are only meaningful for those users who can receive them. So, besides his/her private key, a MBMS service user shall also need to know the MBMS service group keys. [0015] As for a group of users that locate in a certain service region and are receiving the same kind of MBMS service, the group keys used for the encryption of MBMS service data shall be the same in order to make use of radio resources and network resources efficiently, since MBNS is a point-to-multipoint service. Therefore, users needn't to change different group keys due to their movements within the service range of the MBMS service. But in many situations, this group key shall be updated constantly. For example, when a user leaves active so as not to receive current MBMS service any more, or the user is regarded not suitable to receive current MBMS service any more by the network and then made to leave passively for some reason like accounting, the group keys need to be updated and to be notified to all other users to avoid that the user can continue to receive MBMS service by making use of the old group key. [0016] In existing systems, the assignment of group keys is generally performed in two ways: i.e. one-by-one transmission by point-to-point transfer for each user or transmission by point-to-multipoint broadcast for all users. As for one-by-one transmission by point-to-point transfer, the transmission of the group key are encrypted by the corresponding private key for each user in the MBMS service group, which can guarantee that information delivered to the user won't be utilized by other users. If the number of members in group is large and the members varies constantly, this mode will bring extremely heavy load on the system since the system needs to notify each of the members in group one by one by point-to-point transfer for each key update process. Thus, it will take a long time for updating group key each time, thereby reducing the efficiency greatly. While performning the assignment by point-to-multipoint broadcast for all users, the new group key is encrypted by using the old group key and is transmitted by broadcast; user can make use of the old group key for decryption to obtain the new group key. As the user having left the MBMS service may still keep the old group key, he/she may make use of the old group key for decryption to obtain the new group key. So, the problem of insecurity for key exposure exists in this key assignment method by point-to-multipoint broadcast. SUMMARY OF THE INVENTION [0017] Therefore, it is an object of the invention to provide a safe and highly efficient key management and assignment method suitable for multimedia broadcasting or multicasting service that can alleviate system load and reduce time expense. [0018] To achieve the aim, a method for key management and assignment in MBMS service includes following steps: [0019] A group key locates in the root node on the highest layer, which has only child nodes but has no parent nodes; [0020] Private keys corresponding to users locate in leaf nodes, which are the users of MBMS service; [0021] Intermediate node, which owns both a parent node and one or more child nodes, has its own key. [0022] To achieve another aspect of the above object, a method for key management and assignment for information encryption in a radio network system which includes a root node, plurality of intermediate nodes in the root node and plurality of leaf nodes in each intermediate nodes of the radio network system providing Multimedia Broadcast or Multicast service, comprising the steps of: Continue reading... Full patent description for Ciphering key management and distribution in mbms Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Ciphering key management and distribution in mbms patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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